The invention relates to machines for making hot beverages, such as coffee, tea and chocolate. More particularly, the invention relates to improvements in machines of the type wherein a stream of water or another liquid (such as milk) is caused to flow from a container in or on the housing of the machine, through an electric heater and into a holder for a supply of flavoring agent, such as comminuted coffee beans, tea leaves, chocolate powder or the like.
Machines of the above outlined character are known and are in extensive use. In many instances, the conduit means for conveying hot water or another liquid from the electric heater to the holder for a supply of flavoring agent comprises a riser which discharges hot water into the holder, and the latter has a sealable outlet at level above a support (such as a warming plate) for a coffee pot, a teapot or any other suitable vessel for heated beverages.
The electric heaters of presently known coffee making and like machines normally comprise a metallic tube which is mounted on a carrier and contains a heating spiral. The latter is normally embedded in a supply of magnesium oxide powder. The metallic tube is adjacent a conduit which conveys the liquid to be heated. A heater of the just outlined character normally comprises a substantially U-shaped metallic tube for the heating spiral and a substantially U-shaped conduit for the liquid. Cold liquid enters by way of one leg of the U-shaped conduit, and heated liquid leaves the heater by way of the other leg of such conduit.
A drawback of the just described electric heaters is that the rate of heat transfer between the metallic pipe and the liquid in the conduit is not very satisfactory. Moreover, such heaters generate noise and their initial cost is high. Still further, these heaters must be used jointly with auxiliary components such as thermostats and/or specially designed safety fuses. Certain electric heaters of the above outlined character further employ a diode, especially if the machine is to be converted from the making of a relatively small quantity of coffee or another beverage to the making of a larger quantity of such beverage or vice versa. The diode is used to conform the quantity of electrical energy which is supplied to the heating spiral to the selected quantity of the beverage. Such auxiliary components contribute significantly to the cost of the machine and render it prone to malfunction.